Aircooled cylinder head

ABSTRACT

A cylinder head for a twin overhead valve air-cooled internal combustion engine comprising an upper plate and a lower plate so interconnected by valve ports, ribs and walls to define passages through which cooling air can flow. The ribs and walls extend from air inlet places to the vicinity of an injection nozzle and said valve ports substantially parallel to the cylinder axis and obliquely to a plane of symmetry of the cylinder head passing parallel to said cylinder axis through a central cooling air duct in the cylinder head. The valve ports extend transversely to the said plane of symmetry substantially over the entire width of the cylinder head. Cooling air guide walls surround the cylinder head on sides thereof adjacent said air inlet places and extend at least approximately as far as said valve ports. These guide walls are arranged so that cooling air flows partly over the sides of the valve ports which are nearest to said ribs and walls but otherwise is forced to flow through said central cooling air duct.

United States Patent Lohr et al.

[451 Mar. 21, 1972 [54] AIRCOOLED CYLINDER HEAD [72] Inventors: Ludwig Lohr, Lampertheim; Karl Hellwig,

Weiheim, both of Germany [73] Assignee: Farymann Diesel, Farny & Weidmann, Lampertheim, Germany [22] Filed: Dec. 16, 1970 [21] Appl. No.: 98,764

FOREIGN PATENTS OR APPLICATIONS 523,515 10/1953 Belgium ..l23/41.69

877,560 9/l96l GreatBritain ..l23/4l.69

Primary Examiner-Al Lawrence Smith Anorneywaters, Roditi, Schwartz & Nissen [57] ABSTRACT A cylinder head for a twin overhead valve air-cooled internal combustion engine comprising an upper plate and a lower plate so interconnected by valve ports, ribs and walls to define passages through which cooling air can flow. The ribs and walls extend from air inlet places to the vicinity of an injection nozzle and said valve ports substantially parallel to the cylinder axis and obliquely to a plane of symmetry of the cylinder head passing parallel to said cylinder axis through a central cooling air duct in the cylinder head. The valve ports extend transversely to the said plane of symmetry substantially over the entire width of the cylinder head. Cooling air guide walls surround the cylinder head on sides thereof adjacent said air inlet places and extend at least approximately as far as said valve ports. These guide walls are arranged so that cooling air flows partly over the sides of the valve ports which are nearest to said ribs and walls but otherwise is forced to flow through said central cooling air duct.

7 Claims, 5 Drawing Figures AIRCOOLED CYLINDER HEAD BACKGROUND OF THE INVENTION The present invention relates to a cylinder head for an aircooled internal combustion engine having two overhead valves, substantially comprising a lower plate which forms the cylinder head underside, and an upper plate which forms the base of a housing for a valve drive, and is so connected to thelower plate by intermediate parts such as valve ports, walls or ribs, that between the upper and lower plates and intermediate parts passages are defined for the flow of cooling air, and also having an injection nozzle which is arranged in the flow of cooling air upstream of a central cooling air duct which is situated above the web portion between valve seats provided in the cylinder head and is bounded substantially by the valve ports and by said upper and lower plates.

A cylinder head of the above mentioned general type is already known, and regions thereof which particularly require cooling include the web portion between the valve seats, the exhaust valve port and the injection nozzle.

SUMMARY OF THE INVENTION Accordingly it is a primary objective of the invention to provide a new and improved cylinder head which ensures improved cooling of the foregoing regions and thus improves the working reliability of an air'cooled internal combustion engine fitted with said cylinder head.

In order to implement these and still further objects of the invention which will become more readily apparent as the description proceeds, the inventive cylinder head comprises a cylinder head for an air-cooled internal combustion engine having two overhead valves, said cylinder head comprising, a) a lower plate which forms the cylinder head underside, b) valve ports opening into valve seats provided in said lower plate, c) an upper plate which forms the base of a housing for a a valve drive, and which is so connected to said lower plate by intermediate parts such as said valve ports that said upper plate and said lower plate define therebetween with said intermediate parts, passages for the throughflow of cooling air, d) an injection nozzle which is arranged in the cooling air flow upstream of a central cooling air duct which is situated above a web portion between said valve seats and is bounded substantially by said valve ports and said upper and lower plates, e) inlet ribs and inlet guide walls forming part of said intermediate parts extending from the places (A,A) at which the cooling air enters said passages to places in the vicinity of saidv injection nozzle and valve ports, the surfaces of said ribs and walls extending parallel to the cylinder axis and obliquely relative to a plane of symmetry of the cylinder head which extends through said central cooling air duct and also parallel to said cylinder axis, f) said valve ports extending transversely with respect to said plane of symmetry substantially over the entire width of the cylinder head, and g) guide walls for the cooling air which surround the cylinder head at its outer sides which are adjacent the places (A,A) at which the cooling air enters, said guide walls extending at least approximately as far as said valve ports and being so arranged that the cooling air partly flows past the sides of the valve ports which are nearest the inlet ribs and the inlet guide walls but otherwise is obliged to flow through the central cooling air duct.

Feature e) has the effect that cooling air coming for example from a cooling air fan, usually arranged at one side of the cylinder head, is conducted to the aforesaid places requiring cooling without any sharp change of direction and therefore without pressure or speed losses.

Features f) and g) together have the effect that most of the cooling air is forced to flow through the central cooling air duct, thus intensively cooling the injection nozzle and web portion. At the same time the cooling of both valve ports is ensured. This method of cooling makes it possible to construct the cylinder head with identical valve ports, each of which can be used both as an inlet port and as an exhaust port, so that in he case of V-type engines an advantageous possibility is afforded as regards the arrangement of the inlet and exhaust manifolds.

Improved heat dissipation from the 'web portion is advantageously achieved by arranging between the central cooling air duct and the outer side of the cylinder head, where the cooling air issues, a central cooling rib between the upper plate and lower plate in the plane of symmetry of the cylinder head.

Improved heat dissipation from the valve port used as the exhaust port is advantageously obtained by cooling ribs provided for at least one valve port, in the vicinity of the region covered by a guide wall, said cooling ribs extending at right angles to the cylinder axis. The arrangement of the cooling ribs at right angles to the cylinder axis makes it possible in the cylinder head of the present invention to provide the largest possible rib surface area contacted by cooling air, with an appropriately large heat conduction cross section.

In cases where the arrangement of cooling ribs at the inlet side of the valve port used as exhaust port is not possible, for example since space has to be provided at this place for a heater plug or a sparking plug holder, adequate cooling can advantageously be achieved by making the guide wall at one valve port terminate short of the valve port so as to leave free an outlet aperture for the cooling air, whereby cooling air can flow past the valve port into the free atmosphere.

The surface of the cylinder head subjected to the cooling air can advantageously be increased in size by providing the inlet guide wall, where a guide wall surrounds the cylinder head in the vicinity of an inlet guide wall, with cooling ribs which extend at right angles to the cylinder axis.

The flow of cooling air issuing from the central cooling air duct can advantageously be further used for the cooling of the cylinder head by arranging at both sides adjacent the central cooling rib in each case further cooling ribs which are arranged approximately parallel thereto.

The cooling of the valve port used as the exhaust port can advantageously be improved by providing the valve ports in the vicinity of the outer side of the cylinder head at which the cooling air issues, with cooling ribs which extend at right angles to the cylinder axis.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than set forth above, will become apparent, when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a section through an inventive cylinder head taken along the line 1-1 in FIG. 2,

FIG. 2 is a section through the cylinder head taken along the line IIII of FIG. 1,

FIG. 3 is a section through the cylinder head taken along the line III-III of FIG. 2,

FIG. 4 is a view of the cylinder head with guide walls removed, taken in the direction of the arrow IV in FIG. I, and

FIG. 5 is a view of the cylinder head with guide walls removed, taken in the direction of the arrow V in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, it will be observed by reference thereto, that the exemplary illustrated embodiment of the inventive cylinder head for an air-cooled internal combustion engine having two overhead valves comprises a lower plate 1 which is connected to the upper plate 2 by intermediate parts in the form of valve ports 3 and 4, inlet guide walls 5 and 6, inlet ribs 7 and 8, and cooling ribs 9, l0 and 11. The lower plate 1 forms the cylinder head underside for cooperation with a cylinder of the internal combustion engine, which is not otherwise shown, and contains valve seats 12 and 13 for the two overhead valves (also not shown). The upper plate 2 forms the base of a housing (also not shown) for a valve drive. Between the plates 1 and 2, the walls 5 and 6, and the ribs 7,8,9,10 and 11, and also the valve ports 3 and 4 are situated passages through which the cooling air entering in the direction of the arrows A,A can flow. The valve ports 3 and 4, the lower plate 1 and the upper plate 2 substantially define a central cooling air duct 14 which is situated above a web portion 15 between the valve seats 12 and 13.

The duct 14 is sub-divided by the cooling rib 9 into two part-ducts. In the cooling air flow is arranged an injection nozzle 16 upstream of the web portion 15. The surfaces of the ribs 7,8,9,l and 11, and of the inlet guide walls 5 and 6, extend parallel to the cylinder axis 17. The inlet guide walls 5 and 6 and the inlet ribs 7 and 8 extend at right angles to a plane of symmetry 18 of the cylinder head which plane itself extends parallel to the cylinder axis 17 or coincides therewith. The parts 5,6,7 and 8 extend from the outer sides 19 and 20, at which the cooling air enters as indicated by the arrows A,A into the vicinity of the injection nozzle 16 and the valve ports 3 and 4 respectively. The latter extend transversely to the plane of symmetry 18 substantially over the entire width of the cylinder head.

At the outer side 19 and at the neighboring outer sides 20 and 21 the cylinder head is surrounded by guide walls 22 and 23 for the cooling air. The wall 22 is taken as far as the valve port 3, whereas the wall 23 terminates short of the valve port 4 and leaves an outlet aperture 24 free in the vicinity of the valve port 4. In this way it is possible to cool the valve port 4 effectively by means of the air flowing through the aperture 24 despite the presence of a sparking plug holder (not shown) which is inserted in the bore 25 and which prevents the arrangement of cooling ribs at this place.

The cooling rib 9 is arranged between the central cooling air duct 14 and the outer side 26 at which the cooling air issues, and extends between the upper plate 2 and lower plate 1 in the plane of symmetry 18. The valve port 3 is provided in the vicinity of the guide wall 22 with cooling ribs 27 which extend at right angles to the cylinder axis 17 up to the cooling rib 8 and merge into the latter. The inlet guide wall 6 is provided in the vicinity of the guide wall 23 with cooling ribs 28 which extend at right angles to the cylinder axis 17. Adjacent the cooling rib 9 the cooling ribs and l l are arranged approximately parallel thereto. The valve ports 3 and 4 are provided at their sides nearest to the outer side 26 with cooling ribs 29 which extend at right angles to the cylinder axis 17 up to the ribs 11 or merge into them.

Of the cooling air entering in the direction of the arrows A,A, a part-flow B cools the valve port 3, the ribs 27 contributing to increasing the size of the heat-dissipating surface. A further part flow C flows along the valve port 4, cooling the latter, and through the aperture 24 out into the free atmosphere. Also flowing into the free atmosphere is a part flow D which dissipates heat from the lower plate 1 at the ribs 28 over the guide wall 6. However, the main quantity of cooling air flows through the central cooling air duct 14 and cools the web portion and the injection nozzle 16. The cooling rib 9 has the result of increasing the heat-dissipating surface at the web portion 15. The cooling air issuing from the central cooling air duct 14 in the direction towards the outer side 26 is also used for cooling the cylinder head, the cooling ribs 10, 11 and 29, the latter more particularly at the valve ports 3 and 4, contributing to increasing the size of the heat-dissipation effect. The cooling ribs 30 arranged about the lower plate 1 also improve dissipation of heat from this part.

While there is shown and described a present preferred embodiment of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

What is claimed is:

l. A cylinder head for an air-cooled internal combustion engine having two overhead valves, said cylinder head comprising,

a. a lower plate (1) which forms the cylinder head underside, b. valve ports (3,4) opening into valve seats (12,13) provided in said lower plate (1 c. an upper plate (2) which forms the base of a housing for a valve drive, and which is so connected to said lower plate (1) by intermediate parts such as said valve ports (3,4) that said upper plate and said lower plate define therebetween with said intermediate parts, passages for the throughflow of cooling air, an injection nozzle (16) which is arranged in the cooling air flow upstream of a central cooling air duct (14) which is situated above a web portion (15) between said valve seats (12,13) and is bounded substantially by said valve ports and said upper and lower plates, e. inlet ribs (7,8) and inlet guide walls (5,6) forming part of said intermediate parts extending from the places (A,A) at which the cooling air enters said passages to places in the vicinity of said injection nozzle (16) and valve ports (3,4), the surfaces of said ribs and walls extending parallel to the cylinder axis (17) and obliquely relative to a plane of symmetry (18) of the cylinder head which extends through said central cooling air duct (14) and also parallel to said cylinder axis (17), said valve ports (3,4) extending transversely with respect to said plane of symmetry (18) substantially over the entire width of the cylinder head, and

g. guide walls (22,23) for the cooling air which surround the cylinder head at its outer sides (19,20,21) which are adjacent the places (A,A) at which the cooling air enters, said guide walls extending at least approximately as far as said valve ports (3,4) and being so arranged that the cooling air partly flows past the sides of the valve ports which are nearest the inlet ribs (7,8) and the inlet guide walls (5,6) but otherwise is obliged to flow through the central cooling air duct (14).

2. A cylinder head according to claim 1, including a central cooling rib (9) located between said central cooling air duct (14) and the outer side (26) of the cylinder head where the cooling air flows out, said central cooling rib (9) being arranged between said upper plate (2) and said lower plate (1) in said plane of symmetry (18) of the cylinder head.

3. A cylinder head according to claim 1, wherein at least one of said valve ports (3) is provided, in the vicinity of the region covered by one of said guide walls (22), with cooling ribs 27) which extend at right angles to said cylinder axis (17).

4. A cylinder head according to claim 1, wherein at least at one of said valve ports (4) one of said guide walls (23) terminates short of said one of said valve ports so that an outlet aperture (24) is defined between said one of said guide walls (23) and said one of said valve ports (4), whereby a flow of cooling air can flow past said valve port (4) into the free atmosphere.

5. A cylinder head according to claim 1, wherein where one of said guide walls (23) surrounds the cylinder head in the vicinity of one of said inlet guide walls (6), this inlet guide wall (6) is provided with cooling ribs (28) which extend at right angles to the cylinder axis (17).

6. A cylinder head according to claim 2, including further cooling ribs (10,11) arranged at both sides adjacent the central cooling rib (9), said further cooling ribs (10,11) being approximately parallel to said central cooling rib (9).

7. A cylinder head according to claim 1, wherein said valve ports (3,4) are provided in the vicinity of the outer side (26) of the cylinder head at which the cooling air issues, with cooling ribs (29) which extend at right angles to the cylinder axis (17). 

1. A cylinder head for an air-cooled internal combustion engine having two overhead valves, said cylinder head comprising, a. a lower plate (1) which forms the cylinder head underside, b. valve ports (3,4) opening into valve seats (12,13) provided in said lower plate (1), c. an upper plate (2) which forms the base of a housing for a valve drive, and which is so connected to said lower plate (1) by intermediate parts such as said valve ports (3,4) that said upper plate and said lower plate define therebetween with said intermediate parts, passages for the throughflow of cooling air, d. an injection nozzle (16) which is arranged in the cooling air flow upstream of a central cooling air duct (14) which is situated above a web portion (15) between said valve seats (12,13) and is bounded substantially by said valve ports and said upper and lower plates, e. inlet ribs (7,8) and inlet guide walls (5,6) forming part of said intermediate parts extending from the places (A,A) at which the cooling air enters said passages to places in the vicinity of said injection nozzle (16) and valve ports (3,4), the surfaces of said ribs and walls extending parallel to the cylinder axis (17) and obliquely relative to a plane of symmetry (18) of the cylinder head which extends through said central cooling air duct (14) and also parallel to said cylinder axis (17), f. said valve ports (3,4) extending transversely with respect to said plane of symmetry (18) substantially over the entire width of the cylinder head, and g. guide walls (22,23) for the cooling air which surround the cylinder head at its outer sides (19,20,21) which are adjacent the places (A,A) at which the cooling air enters, said guide walls extending at least approximately as far as said valve ports (3,4) and being so arranged that the cooling air partly flows past the sides of the valve ports which are nearest the inlet ribs (7,8) and the inlet guide walls (5,6) but otherwise is obliged to flow through the central cooling air duct (14).
 2. A cylinder head according to claim 1, including a central cooling rib (9) located between said central cooling air duct (14) and the outer side (26) of the cylinder head where the cooling air flows out, said central cooling rib (9) being arranged between said uppEr plate (2) and said lower plate (1) in said plane of symmetry (18) of the cylinder head.
 3. A cylinder head according to claim 1, wherein at least one of said valve ports (3) is provided, in the vicinity of the region covered by one of said guide walls (22), with cooling ribs (27) which extend at right angles to said cylinder axis (17).
 4. A cylinder head according to claim 1, wherein at least at one of said valve ports (4) one of said guide walls (23) terminates short of said one of said valve ports so that an outlet aperture (24) is defined between said one of said guide walls (23) and said one of said valve ports (4), whereby a flow of cooling air can flow past said valve port (4) into the free atmosphere.
 5. A cylinder head according to claim 1, wherein where one of said guide walls (23) surrounds the cylinder head in the vicinity of one of said inlet guide walls (6), this inlet guide wall (6) is provided with cooling ribs (28) which extend at right angles to the cylinder axis (17).
 6. A cylinder head according to claim 2, including further cooling ribs (10,11) arranged at both sides adjacent the central cooling rib (9), said further cooling ribs (10,11) being approximately parallel to said central cooling rib (9).
 7. A cylinder head according to claim 1, wherein said valve ports (3,4) are provided in the vicinity of the outer side (26) of the cylinder head at which the cooling air issues, with cooling ribs (29) which extend at right angles to the cylinder axis (17). 